This invention relates generally to structures for supporting vehicles and more particularly to racks for storing wheeled container chassis.
Container chassis are used to transport large truck-sized shipping containers. Such containers are used for packaging cargo for easy handling and transportation by ship, truck or rail. The containers are rectangular units which are typically 8 to 9.5 feet high and from 20 to 44 feet in length. Mounted on the upper and lower corners of the containers are ISO (International Standards Organization) corner castings. The containers are handled by lift trucks provided with hoisting attachments including twistlock devices adapted to engage the corner castings at opposite ends of the containers. Examples of such containers and lift trucks are disclosed on pages 9 and 17 in "Container News" of May 1981.
For transportation by truck, the containers are positioned on a wheeled container chassis, examples of which are disclosed on page 10 of the aforementioned magazine. The container is held in place by twist lock devices which protrude upwardly from the top of the chassis to engage the corner castings.
Since container chassis are very large, approximately 45 feet in length, their storage can be a problem. If much storage space is available, each chassis can be stored in a generally horizontal position with its wheels on the ground. However, this manner of storage is impractical in areas, such as seaports and railroad yards, where large numbers of the chassis accumulate and in which storage space is scarce.
In order to reduce the storage space requirements of container chassis, several methods of stacking have been devised. In one method, the container chassis are stacked horizontally one atop the other, with their wheels down. However, because stacking in this manner is unstable, only three chassis can be placed safely in a single stack. In an attempt to increase the number of chassis which can be stacked in a limited area, another stacking method calls for turning every other chassis in the stack upside down. In this way, as many as five chassis can be stacked safely. However, conventional methods of flipping the chassis upside down frequently damage the chassis. Moreover, both of the foregoing stacking methods cause uneven utilization of the stacked chassis. Because the first chassis in the stack is at the bottom of the stack and therefore less accessible, it is less likely to be used than the chassis at the top of the stack.
In an attempt to overcome some of the deficiencies of the foregooing stacking methods, Multi-Sort, Inc. of Portland, Oreg., devised a rack for stacking container chassis in an approximately vertical position. In top plan view, this rack has a generally U-shape with an opening at one end of the rack. A series of horizontally pivoting arms are mounted along one side of the rack and at the top thereof. A container chassis is positioned in the rack by hoisting it into a vertical position with a lift truck and moving it wheels first into the open end of the rack. The chassis is then placed in the rack with its rear end resting on the ground and the underside of its frame resting against the closed end of the rack. The first pivot axis is then swung across the rack and latched into position so that another container chassis can be leaned against it.
This method of storage reduces the storage area required by the container chassis, but has several drawbacks. First, like the aforementioned ground stacking systems, this rack provides a first in, last out storage system, resulting in uneven utilization of the chassis. Second, it requires a special lift truck attachment designed so that the lift truck approaches an empty chassis from its rear end. The attachment is tilted down to grasp the chassis along opposite sides of its frame and then tilted back up to lift the chassis into an upright position. A third disadvantage of this rack is the difficulty in storing the container chassis off the ground. The rear end of the chassis frame is provided with rear taillights and other breakable parts. If the chassis is stood on its rear end, these parts are susceptible to damage. The chassis wheels can be rested on wheel chocks, but the chocks must be removed from the empty storage positions in order to provide free access for the lift truck into the rack. Finally, efficient use of this rack requires two people, one to operate the lift truck and the other to manipulate the wheel chocks and horizontally-pivoting arms. Otherwise, the operator of the lift truck must get off the lift truck to perform these steps each time a chassis is placed in or removed from the rack.
It would be preferable to be able to stack the container chassis so that the first chassis stored can be the first chassis removed from storage for use, thereby enabling more uniform utilization of all the stored chassis. It would also be preferable to be able to handle empty container chassis by means of lift truck apparatus adapted for approaching and engaging the chassis along one side so that the need for special chassis-handling apparatus is minimized. Ideally, the stacking system should also require only one person to perform all steps in the storage process from the seat of a lift truck.
A variety of storage systems for automobiles are known. U.S. Pat. Nos. 1,280,512 to Macomber and 1,978,287 to Thomas disclose frame structures inclined at 20.degree.-40.degree. angles for supporting automobiles in a railroad car. To prevent rolling, the wheels of the automobiles are secured in a cradle by chains. U.S. Pat. No. 3,677,193 to Pringle discloses a railroad car in which automobiles are stored on their side, supported along a wall by brackets connected to the underside of their chassis. U.S. Pat. Nos. 3,613,914 to Jaekle, et al.; 3,752,085 to Venditty and 3,872,983 to Chapman disclose railroad cars designed to support automobiles on end, supported on tiltable sidewalls of the freight cars by brackets connected to the underside of the chassis of the automobiles.
However, none of the foregoing patents discloses means for solving the above-described problems connected with the storage of wheeled container chassis. In particular, none of these patents discloses a storage apparatus into which a container chassis could be loaded sideways. Nor do they disclose means for supporting a container chassis vertically above ground level without positive securement.
Accordingly, there remains a need for an improved arrangement for storing wheeled container chassis.